Bi₂Te₃ Nanowire Assembly And An Analysis Of Its ?-? Characteristics

As the size of phase change memories shrinks,the study of phase change material nanowires is of great value.Nanowires can not only be used as a test system to study the effects of dimensions and sizes on the physical properties of materials,but also as a component of new nanodevices.This thesis focuses on the self-assembly method and electrical properties of Bi₂Te₃ nanowires prepared by electrochemical methods.It mainly discusses the following:(1)Mathematical modeling and analysis of Bi₂Te₃ nanoclusters were first performed using MATLAB software.Based on the metal-semiconductor contact,an M-S-M model was established,and the transport parameters of Bi₂Te₃ nanoclusters were extracted from the experimental ?-? curves,such as conductivity,carrier concentration,and mobility.(2)The effects of different Schottky barrier heights and different metal-semiconductor contact areas on the ?-? characteristic curve of nano-devices are simulated by MATLAB,and the conclusion that the Schottky barrier height is the main factor affecting the symmetry of the ?-? curve is obtained.(3)The COMSOL software was used to simulate the electric field and the dielectrophoretic force of assembled electrodes of different shapes.Compared to triangles and rectangles,the width of the stable region of the dielectrophoretic force of the circular electrodes is moderate and more favorable for the assembly of nano wires.The circular electrode is the conclusion that the best electrode for dielectrophoresis assembly.(4)Dielectrophoresis was applied to the assembly of Bi₂Te₃ nanowires,and the dielectric electrophoresis assembly parameters suitable for the material were obtained in a more convenient way.Firstly,the influence of the frequency of dielectric electrophoresis on the assembly of Bi₂Te₃ nanowires was obtained by simulation.According to the assembly experiment,a relatively moderate assembly voltage was quickly obtained.Finally,the effect of time parameters on the assembly effect was discussed through electrode group experiments.It was found that assembly parameters(1V,500KHZ,60s)can produce a single Bi₂Te₃ nanowire with a higher proportion.(5)Electrical tests on a single Bi₂Te₃ nanowire assembled by dielectric electrophoresis have obtained good repeatable phase change characteristics.Under the same conditions,the resistance value of a single Bi₂Te₃ nanowire in the crystalline state is 750KQ which is about twice that of the two nanowires.It proves that the test results are credible and the assembly is stable.